CRISPR-associated protein 12b (Cas12b)

CRISPR-associated protein 12b (Cas12b), formerly known as C2c1, is a programmable, RNA-guided DNA endonuclease belonging to the Type V-B CRISPR-Cas system (Shmakov et al., 2015). Unlike the more common Cas9, Cas12b is typically smaller in size, which facilitates its packaging into viral vectors like adeno-associated virus (AAV) for therapeutic delivery (Strecker et al., 2019). It recognizes a T-rich protospacer adjacent motif (PAM) and generates a staggered double-strand break in the target DNA (UniProt P0DPU3). A unique feature of Cas12b is its dual-nature activity: it performs highly specific cis-cleavage of target DNA and, upon activation, exhibits non-specific trans-cleavage (collateral activity) of single-stranded DNA, a property widely exploited in molecular diagnostics (Mammoth Biosciences). In a therapeutic context, Cas12b is being developed for precise genome editing to treat genetic diseases and for engineering immune cells. However, its application requires careful optimization of temperature stability, as many natural Cas12b variants are derived from thermophilic bacteria and may not function optimally at human body temperature without protein engineering (Teng et al., 2019).

Other names

C2c1CRISPR-associated endonuclease Cas12bType V-B CRISPR-associated protein

RNA-guided site-specific DNA cleavage and collateral (trans) nuclease activity.